Polygonum polygaloides
Polygala knotweed, Polygala Knotweed
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Family: Polygonaceae · Type: Herb · Native
Polygonum polygaloides (Polygala knotweed) is a native California herb in the Polygonaceae family, recognized by limited range data suggests no sympatric congeners.
Polygala knotweed is a California native annual found in dry, open habitats at mid to high elevations. Flowering from June to September, this delicate plant produces white to red flowers in small, compact spike-like clusters less than 3 millimeters long. Growing with slender, wiry green stems 6 to 20 centimeters tall and widely spreading branches, it appears almost threadlike in form. Its narrow linear leaves are small, with blades 10 to 40 millimeters long and less than 2.5 millimeters wide, with margins rolled tightly underneath. The tiny fruits are light yellow to brown, smooth or with faint longitudinal ridges, nestled within the plant's compact flowering structure.
Identification and appearance
Key characters: Geographically isolated; limited range data suggests no sympatric congeners
Habitat and range
California counties: Modoc, San Bernardino, El Dorado, Mono, Sierra, Amador, Alpine, Lassen, Tuolumne, Nevada, Mariposa
How to tell it apart
vs Euphorbia: Polygonum has swollen stem joints with papery sheaths; Euphorbia has milky sap when broken.; vs Persicaria: Hold node sheaths to light—Polygonum's are translucent and split; Persicaria's are opaque and intact.; vs Eriogonum: Polygonum has papery sheaths at nodes; Eriogonum has flowers in cup-like involucres.; vs Acmispon: Polygonum has swollen stem nodes; Acmispon has compound leaves with 3-5 leaflets.; vs Atriplex: Polygonum has papery stem sheaths; Atriplex has mealy or scurfy coating on leaves.
Frequently asked questions
Is Polygonum polygaloides native to California?
Yes. Polygonum polygaloides is native to California (recorded as native).
Where in California does Polygonum polygaloides grow?
Polygonum polygaloides occurs in Modoc, San Bernardino, El Dorado, Mono, Sierra, Amador, Alpine, Lassen and other counties.
What plant family does Polygonum polygaloides belong to?
Polygonum polygaloides is in the Polygonaceae family, genus Polygonum.
Related species
Other California species in the same genus, family, or bioregion.
Sources: Jepson eFlora · Index of California Plant Names · CalPhotos
Last updated 2026-10-07
Data from The California Species Project — 14,000+ California species with verified data from CNPS, CDFW, USFWS, Cal-IPC, and more.